FONTANA, Calif. (KABC) -- A Fontana mother who previously served time for child abuse is now facing murder charges in the death of her 3-year-old daughter, police say.

The child's father is also facing child endangerment charges after police say he failed to take steps to stop his girlfriend from causing harm to their child.

Ana Rojo, the child's aunt, says it happened at the family home Wednesday.

Richard Rojo came home that day to find his girlfriend, Miriam Sandoval Montano, holding their daughter Angela, who wasn't breathing.

"When he got here he tried to do CPR, and he yelled at her, did you call 911, and she said no," Ana Rojo said. "And he's like what are you waiting for? Call 911! And then he got her and he was giving CPR."

Angela Rojo was later pronounced dead.

Police say Montano had been arrested about three years earlier for abuse of her daughter which resulted in broken bones. She confessed, pleaded no contest and served six months of a one-year sentence.

"When a person has the ability to protect a child, has the ability to make decisions that are in the best interest of a child, and they neglect those duties, that is child endangerment," said Officer Jay Sayegh with Fontana police.

Ana Rojo believes her brother didn't want to separate the children from their mother.

"I'm sure he wanted to have his family together, and he saw that the kids were probably going to miss their mom," she said. "But he should have...should have seen the signs, but he said he didn't see the signs, and we were on the phone crying, because he says he never saw anything."

"He always wanted to believe that she was going to do the right thing and that she was better. But she wasn't."

With both parents in jail, two other children in the home are now in custody of the Department of Children and Family Services.